From a556ce8fb872284fe9d20dbe2109458cd50629ff Mon Sep 17 00:00:00 2001
From: Ainar Garipov <a.garipov@adguard.com>
Date: Mon, 20 Feb 2023 18:01:00 +0300
Subject: [PATCH] Pull request 1742: 5518-doh-panic

Updates #5425.
Updates #5518.

Squashed commit of the following:

commit 74873bd47bab569d0a45361f2d87c0e33e0ed3fb
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Feb 20 17:54:44 2023 +0300

    dnsforward: use Host when available

commit 4eee3d655ec7eb84e0327dcf30603578772609e1
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Feb 20 17:24:24 2023 +0300

    dnsforward: fix panic on unencrypted doh
---
 CHANGELOG.md                         |  2 +
 internal/dnsforward/clientid.go      | 17 ++++-
 internal/dnsforward/clientid_test.go | 92 ++++++++++++++++++++--------
 3 files changed, 82 insertions(+), 29 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b817450..a7c05663 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,8 +25,10 @@ NOTE: Add new changes BELOW THIS COMMENT.
 
 ### Fixed
 
+- Panic when using unencrypted DNS-over-HTTPS ([#5518]).
 - Failing service installation via script on FreeBSD ([#5431]).
 
+[#5518]: https://github.com/AdguardTeam/AdGuardHome/issues/5518
 [#5431]: https://github.com/AdguardTeam/AdGuardHome/issues/5431
 
 <!--
diff --git a/internal/dnsforward/clientid.go b/internal/dnsforward/clientid.go
index e44600ba..b48d4a4c 100644
--- a/internal/dnsforward/clientid.go
+++ b/internal/dnsforward/clientid.go
@@ -147,11 +147,24 @@ func (s *Server) clientIDFromDNSContext(pctx *proxy.DNSContext) (clientID string
 	return clientID, nil
 }
 
-// clientServerName returns the TLS server name based on the protocol.
+// clientServerName returns the TLS server name based on the protocol.  For
+// DNS-over-HTTPS requests, it will return the hostname part of the Host header
+// if there is one.
 func clientServerName(pctx *proxy.DNSContext, proto proxy.Proto) (srvName string, err error) {
 	switch proto {
 	case proxy.ProtoHTTPS:
-		srvName = pctx.HTTPRequest.TLS.ServerName
+		r := pctx.HTTPRequest
+		if connState := r.TLS; connState != nil {
+			srvName = connState.ServerName
+		} else if r.Host != "" {
+			var host string
+			host, err = netutil.SplitHost(r.Host)
+			if err != nil {
+				return "", fmt.Errorf("parsing host: %w", err)
+			}
+
+			srvName = host
+		}
 	case proxy.ProtoQUIC:
 		qConn := pctx.QUICConnection
 		conn, ok := qConn.(quicConnection)
diff --git a/internal/dnsforward/clientid_test.go b/internal/dnsforward/clientid_test.go
index d0c0c40d..458b66d3 100644
--- a/internal/dnsforward/clientid_test.go
+++ b/internal/dnsforward/clientid_test.go
@@ -50,136 +50,169 @@ func TestServer_clientIDFromDNSContext(t *testing.T) {
 	testCases := []struct {
 		name         string
 		proto        proxy.Proto
-		hostSrvName  string
+		confSrvName  string
 		cliSrvName   string
 		wantClientID string
 		wantErrMsg   string
+		inclHTTPTLS  bool
 		strictSNI    bool
 	}{{
 		name:         "udp",
 		proto:        proxy.ProtoUDP,
-		hostSrvName:  "",
+		confSrvName:  "",
 		cliSrvName:   "",
 		wantClientID: "",
 		wantErrMsg:   "",
+		inclHTTPTLS:  false,
 		strictSNI:    false,
 	}, {
 		name:         "tls_no_clientid",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "example.com",
 		wantClientID: "",
 		wantErrMsg:   "",
+		inclHTTPTLS:  false,
 		strictSNI:    true,
 	}, {
 		name:         "tls_no_client_server_name",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "",
 		wantClientID: "",
 		wantErrMsg: `clientid check: client server name "" ` +
 			`doesn't match host server name "example.com"`,
-		strictSNI: true,
+		inclHTTPTLS: false,
+		strictSNI:   true,
 	}, {
 		name:         "tls_no_client_server_name_no_strict",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "",
 		wantClientID: "",
 		wantErrMsg:   "",
+		inclHTTPTLS:  false,
 		strictSNI:    false,
 	}, {
 		name:         "tls_clientid",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "cli.example.com",
 		wantClientID: "cli",
 		wantErrMsg:   "",
+		inclHTTPTLS:  false,
 		strictSNI:    true,
 	}, {
 		name:         "tls_clientid_hostname_error",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "cli.example.net",
 		wantClientID: "",
 		wantErrMsg: `clientid check: client server name "cli.example.net" ` +
 			`doesn't match host server name "example.com"`,
-		strictSNI: true,
+		inclHTTPTLS: false,
+		strictSNI:   true,
 	}, {
 		name:         "tls_invalid_clientid",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "!!!.example.com",
 		wantClientID: "",
 		wantErrMsg: `clientid check: invalid clientid "!!!": ` +
 			`bad domain name label rune '!'`,
-		strictSNI: true,
+		inclHTTPTLS: false,
+		strictSNI:   true,
 	}, {
 		name:        "tls_clientid_too_long",
 		proto:       proxy.ProtoTLS,
-		hostSrvName: "example.com",
+		confSrvName: "example.com",
 		cliSrvName: `abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmno` +
 			`pqrstuvwxyz0123456789.example.com`,
 		wantClientID: "",
 		wantErrMsg: `clientid check: invalid clientid "abcdefghijklmno` +
 			`pqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456789": ` +
 			`domain name label is too long: got 72, max 63`,
-		strictSNI: true,
+		inclHTTPTLS: false,
+		strictSNI:   true,
 	}, {
 		name:         "quic_clientid",
 		proto:        proxy.ProtoQUIC,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "cli.example.com",
 		wantClientID: "cli",
 		wantErrMsg:   "",
+		inclHTTPTLS:  false,
 		strictSNI:    true,
 	}, {
 		name:         "tls_clientid_issue3437",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "cli.myexample.com",
 		wantClientID: "",
 		wantErrMsg: `clientid check: client server name "cli.myexample.com" ` +
 			`doesn't match host server name "example.com"`,
-		strictSNI: true,
+		inclHTTPTLS: false,
+		strictSNI:   true,
 	}, {
 		name:         "tls_case",
 		proto:        proxy.ProtoTLS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "InSeNsItIvE.example.com",
 		wantClientID: "insensitive",
 		wantErrMsg:   ``,
+		inclHTTPTLS:  false,
 		strictSNI:    true,
 	}, {
 		name:         "quic_case",
 		proto:        proxy.ProtoQUIC,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "InSeNsItIvE.example.com",
 		wantClientID: "insensitive",
 		wantErrMsg:   ``,
+		inclHTTPTLS:  false,
 		strictSNI:    true,
 	}, {
 		name:         "https_no_clientid",
 		proto:        proxy.ProtoHTTPS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "example.com",
 		wantClientID: "",
 		wantErrMsg:   "",
+		inclHTTPTLS:  true,
 		strictSNI:    true,
 	}, {
 		name:         "https_clientid",
 		proto:        proxy.ProtoHTTPS,
-		hostSrvName:  "example.com",
+		confSrvName:  "example.com",
 		cliSrvName:   "cli.example.com",
 		wantClientID: "cli",
 		wantErrMsg:   "",
+		inclHTTPTLS:  true,
+		strictSNI:    true,
+	}, {
+		name:         "https_issue5518",
+		proto:        proxy.ProtoHTTPS,
+		confSrvName:  "example.com",
+		cliSrvName:   "cli.example.com",
+		wantClientID: "cli",
+		wantErrMsg:   "",
+		inclHTTPTLS:  false,
+		strictSNI:    true,
+	}, {
+		name:         "https_no_host",
+		proto:        proxy.ProtoHTTPS,
+		confSrvName:  "example.com",
+		cliSrvName:   "example.com",
+		wantClientID: "",
+		wantErrMsg:   "",
+		inclHTTPTLS:  false,
 		strictSNI:    true,
 	}}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			tlsConf := TLSConfig{
-				ServerName:     tc.hostSrvName,
+				ServerName:     tc.confSrvName,
 				StrictSNICheck: tc.strictSNI,
 			}
 
@@ -195,7 +228,7 @@ func TestServer_clientIDFromDNSContext(t *testing.T) {
 
 			switch tc.proto {
 			case proxy.ProtoHTTPS:
-				httpReq = newHTTPReq(tc.cliSrvName)
+				httpReq = newHTTPReq(tc.cliSrvName, tc.inclHTTPTLS)
 			case proxy.ProtoQUIC:
 				qconn = testQUICConnection{
 					serverName: tc.cliSrvName,
@@ -222,20 +255,25 @@ func TestServer_clientIDFromDNSContext(t *testing.T) {
 }
 
 // newHTTPReq is a helper to create HTTP requests for tests.
-func newHTTPReq(cliSrvName string) (r *http.Request) {
+func newHTTPReq(cliSrvName string, inclTLS bool) (r *http.Request) {
 	u := &url.URL{
 		Path: "/dns-query",
 	}
 
-	return &http.Request{
+	r = &http.Request{
 		ProtoMajor: 1,
 		ProtoMinor: 1,
 		URL:        u,
 		Host:       cliSrvName,
-		TLS: &tls.ConnectionState{
-			ServerName: cliSrvName,
-		},
 	}
+
+	if inclTLS {
+		r.TLS = &tls.ConnectionState{
+			ServerName: cliSrvName,
+		}
+	}
+
+	return r
 }
 
 func TestClientIDFromDNSContextHTTPS(t *testing.T) {